Engines, such as those which power aircraft and industrial equipment, may employ a compressor to compress air that is drawn into the engine and a turbine to capture energy associated with the combustion of a fuel-air mixture. An engine may include an exhaust section that exhausts gases resulting from the combustion from the engine. A turbine exhaust case (TEC) is a component that is typically included in the exhaust section. Various embodiments of a TEC are shown and described in United States patent application publication number 2016/0201490, the contents of which are incorporated herein by reference.
Referring to FIG. 2A, an example of a TEC 200 in accordance with the prior art is shown. The TEC 200 is shown arranged relative to an axial/longitudinal centerline 202 (where the centerline 202 may correspond to a centerline of an engine). Axial, radial, and circumferential directions are superimposed in FIG. 2A for reference purposes.
The TEC 200 includes a first, outer case 204 and a second, inner case 208. The cases 204 and 208 are coupled to one another by several vane strut assemblies 212 that are distributed around the circumference of the TEC 200. For purposes of illustrative/descriptive convenience, a given one of the vane strut assemblies 212 (identified as vane strut assembly 212a) is shown in a removed/extracted state/position relative to, e.g., the cases 204 and 208 in FIG. 2A.
Referring to FIGS. 2A-2B, the vane strut assembly 212a includes a first panel 222a and a second panel 222b. The panels 222a and 222b are circumferentially separated from one another. A pressurized cooling flow (denoted as P Bypass in FIG. 2B) is included in the region between the panels 222a and 222b to cool the vane strut assembly 212a. An exhaust gas flow/exhaust gases (denoted as P Gas Pass in FIG. 2B) is/are present between circumferentially adjacent vane strut assemblies 212.
The operating shape/profile of a vane strut assembly (e.g., the vane strut assembly 212a), which is partially dependent on the cooling flow P Bypass described above, impacts the aerodynamic behavior of the exhaust gases P Gas Pass flowing through the TEC 200. One or more rigid (cylindrical) pins (e.g., pin 230) connect the panels 222a and 222b to control relative tangential/circumferential deflection of the panels 222a and 222b (where the circumferential deflection is represented by a first load/deflection C1 on the first panel 222a and a second load/deflection C2 on the second panel 222b), where that control in turn influences the exhaust gases P Gas Pass. The loads/deflections C1 and C2 result in a tensile/reaction force F that is imposed on the pin 230.
Since relative axial deflections (e.g., deflections A1 and A2) and relative radial deflections (e.g., deflections R1 and R2) of the panels 222a and 222b can differ significantly during engine operation, a large bending stress may be induced in the pin(s). In particular, the axial deflections A1 and A2 and/or the radial deflections R1 and R2 may tend to induce a moment M in the panels 222a and 222b and the pin 230. As a result, the hardware shown in FIGS. 2A-2B is over-designed/over-engineered to accommodate/withstand the moment M. For example, additional material is included in the hardware (above a baseline amount of material) to ensure the reliability of the hardware (e.g., to ensure that the hardware remains operable).